camshaft, or camshaft In English, it is one of the most important parts of our car's engine. It is located in the cylinder head and is responsible for controlling the opening and closing of valves where the air-fuel mixture enters and exits inside the cylinders.
The shape of the camshaft is decisive for the behavior of the vehicle. This piece has a specific shape that gives it special qualities. specific to the engine, because the valves can be open more or less time and can also be opened more or less as required.
where is the camshaft
The position of the camshaft in current engines is at the top, in the cylinder head. More specifically, on specific supports for it, located on the stock itself.
Depending on the engine we are talking about, we can find engines with two camshafts in the same butt. One of them controls the intake valves and the other the exhaust valves. This allows independent control of both systems.
Nor should we forget the engines that have more than one butt, as is the case with engines with V-shaped cylinders. They can also have a tree in each culada or two.
En the old engines, the camshaft(s) could be located in other places depending on where they had the valves and the type of distribution. The current ones are called Overhead Cam (OHC), indicating that placement at the top. However, others in deprecation had them:
- near the bench where the crankshaft is located As is the case with motors. Side Valves (SV), which as its name suggests had the valves on the side.
- in the block. As in the engines Over Head Valves (OHV), which had the valves in the upper part (cylinder head) like the current ones, but the tree was lower. This opened the valves by means of push rods and rocker arms.
Take a look at article on Distribution Types for more information on this.
How does the camshaft work?
camshaft and valves
As you can see in the pictures, the camshaft is a bar with several protrusions. As they rotate, these bumps or cams, tighten the tappets that are attached to the valves. This is how they push them to open at the right time and thus let the air in or let the exhaust gases escape depending on their task.
he camshaft and crankshaft
The camshaft belongs to the timing system the motor. It needs perfect synchronization to work, so it is attached to the crankshaft by means of a timing belt or chain, so that move perfectly even with him.
On four-stroke vehicles, each two turns of the crankshaft it is produced one revolution of the camshaft. What is achieved thanks to the difference in size of the gear wheels that are attached to them.
camshaft sensor
To this synchronization system we must add the camshaft position sensor or CMP, which allows the engine control module (ECM) to know what position it is in at any given time. This synchronizes fuel injection, which is another key element for the engine.
To work, this sensor has a copper coil wound on a magnet core. With the, measures the strength of the magnetic field which is generated by rotating. Thanks to this, it obtains data such as the speed of the motor and the proximity of the metal rotor to the sensor. so you know the position of piston number 1. The others, you know where they are based on the position of this one.
Camshaft faults
Lack of lubrication
It is very important use a suitable oil for our engine, as well as making the changes when the manufacturer tells us. In this way the camshaft will remain perfectly greased, as it is very important for the proper functioning of the engine.
The continual movement of this component causes any lack of excessive lubrication to go reducing its useful life considerably. Also, when the oil is all the way down, because the car hasn't been used for many days, it takes time for the oil pump to send it to the top of the engine. A situation that in some engines causes hydraulic lifter problems and the consequent clacking noise.
This is not a direct problem with the crankshaft, but it can end up affecting it, because the tappets wear out the cams. Which brings us to the next breakdown.
Cam Wear
It is not a common failure in current cars, since many camshafts are forged and have a very high resistance. And much less with the use given by an individual, in which certain mileages are rarely exceeded. However, in some models this breakdown has occurred due to the lower cost of some materials and/or their lower quality.
In any case, although it is not common in most cars, it can be seen more frequently in motorcycle camshafts. This is mainly due to the higher RPM regime at which their engines work.
Axial clearance (of shaft)
If slack is created at the camshaft holders, will be heard rattling or screeching. Which can lead to very severe engine damage if it continues to be used. Typically, this problem is caused by lack of lubrication. So it usually requires repairs beyond the clearance itself, unless it has occurred over time and with abnormally high mileage.
Price of a camshaft
A breakage or failure of the camshaft is very rare. However, we must know that if we need to replace this part, it is a very expensive part, so repair can be very expensive. If it has to be changed, the normal thing is that the workshop invoice is around 1.000 euros in general models. A cost that can be even higher in premium brands or if there are more damaged components.
Images – Peter Anderson, George, Pete, Nathanael Burton, Alexander Lindquist, Mazda Mxtree